首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6422篇
  免费   328篇
  国内免费   36篇
耳鼻咽喉   53篇
儿科学   151篇
妇产科学   127篇
基础医学   879篇
口腔科学   241篇
临床医学   468篇
内科学   1524篇
皮肤病学   415篇
神经病学   523篇
特种医学   152篇
外科学   674篇
综合类   15篇
预防医学   237篇
眼科学   127篇
药学   528篇
中国医学   18篇
肿瘤学   654篇
  2023年   42篇
  2022年   63篇
  2021年   140篇
  2020年   79篇
  2019年   120篇
  2018年   148篇
  2017年   132篇
  2016年   150篇
  2015年   160篇
  2014年   185篇
  2013年   233篇
  2012年   366篇
  2011年   406篇
  2010年   222篇
  2009年   206篇
  2008年   382篇
  2007年   357篇
  2006年   369篇
  2005年   380篇
  2004年   394篇
  2003年   357篇
  2002年   363篇
  2001年   114篇
  2000年   113篇
  1999年   106篇
  1998年   64篇
  1997年   55篇
  1996年   49篇
  1995年   43篇
  1994年   41篇
  1993年   37篇
  1992年   77篇
  1991年   83篇
  1990年   74篇
  1989年   68篇
  1988年   64篇
  1987年   69篇
  1986年   68篇
  1985年   54篇
  1984年   38篇
  1983年   35篇
  1982年   25篇
  1981年   25篇
  1980年   17篇
  1979年   35篇
  1978年   17篇
  1972年   22篇
  1970年   17篇
  1969年   19篇
  1968年   16篇
排序方式: 共有6786条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
Ultrastructural and ultracytochemical studies were performed on blast cells from 12 Down's syndrome neonates with transient myeloproliferative disorder (TMD) and 13 Down's syndrome patients with megakaryoblastic leukaemia (MKL), in order to clarify the cytological characteristics of these cells. Average platelet peroxidase-positivity in blast cells of TMD patients was similar to that found in cases of MKL. Blast cells from subjects with TMD contained a number of different granules, namely, alpha granules, those that were myeloperoxidase (MPO)-positive, electron-lucent or basophil-like, and those containing membrane components or ferritin particles. On the other hand, granules found in the blast cells of MKL patients with Down's syndrome included the electron-lucent variety, those with membrane components and a few that were basophil-like, but not alpha and MPO-positive granules nor those containing ferritin particles. A demarcation membrane system was observed in blasts from the TMD group, but not in the MKL group. These findings suggest that blast cells in TMD patients differentiate to megakaryocytes, neutrophils, basphils and erythroblasts, while those in cases of MKL show limited differentiation to immature megakaryocytes, erythroblasts and, sometime, basophils. Such results correspond well with those of culture studies, in which TMD blasts were found to be precursors of various types of blood cells.  相似文献   
135.

Background

The number of home-visit nursing agencies in Japan has greatly increased over the past 20 years since the Japanese government first introduced it in 1992 to meet the increased needs of home-bound elderly. Since then, home-visit nursing has come to serve for a variety of populations such as those with terminal-stage cancer, neurological diseases, psychiatric conditions, or children with chronic conditions; currently the number of agencies has reached 6,801 (as of April 2013). Yet little has been known about the details of their characteristics in terms of patient types or differences/similarities across regions. In this study, we developed a method to categorize home-visit nursing agencies throughout Japan based on their actual service delivery, in order to help improve healthcare policies allowing better services by those agencies.

Methods

We performed a cluster analysis on data from two national databases (Survey of Institutions and Establishments for Long-term Care which is annually administered by the Ministry of Health, Labour and Welfare [dataset 1; n?=?5,161] and Information Publication System for Long-term Care which is annually reported by home-visit nursing agencies to their respective prefectural governments [dataset 2; n?=?4,400, matching rate to data set 1: 84.4%]), in addition to the results from our original nationwide Fax survey of the service delivery system of home-visit nursing agencies (dataset 3; n?=?2,049 matching rate to data set 1: 39.3%).

Results

The cluster analysis suggested five categories for home-visit nursing agencies based on the type of service delivery system. For deciding of these categories, we held 13 panel discussions with specialists to confirm that the categorization of the home-visit nursing agencies appropriately reflected their actual delivery systems. The five categories were: nurse-centered (560, 10.9%), rehabilitation-centered (211, 4.1%), psychiatric-centered (360, 7.0%), urban-centered (1,784, 34.5%), and rural-centered (2246, 43.5%).

Conclusions

This five categorization system of home-visit nursing agencies could ensure appropriate healthcare policies that will allow agencies to provide better home-visit nursing services based on their patient and staff characteristics and regional needs. The findings would be valuable both in Japan as well as in other countries with rapidly growing aging populations.
  相似文献   
136.

Background

Narrow-band imaging (NBI) has been confirmed as a useful endoscopic technique to distinguish neoplasm from normal tissue, on the basis of the enhanced neovascularity of tumor tissue. NBI-guided tissue biopsy for laryngopharyngeal and digestive lesions is a novel methodology, but the feasibility for central nervous system tumors remains unclear. The aim of our study was to evaluate the feasibility of NBI-guided biopsy for intraventricular and paraventricular tumor.

Methods

Fourteen patients with intraventricular or paraventricular tumors underwent neuroendoscopic biopsy using a videoscope with NBI. Ventricular walls and tumors were observed using conventional imaging, followed by NBI. Colors of ventricle walls and tumors visualized using NBI were compared to those visualized under conventional imaging. Extracted specimens were stained using CD31 antibody and numbers of microvessels in each specimen were counted for analyzing vascular density.

Results

Normal ventricle walls were a similar color under conventional imaging and NBI. Tumor surfaces appeared to be cyan in color under NBI. Vessels on the tumor were more clearly visualized with NBI than with conventional imaging. NBI was able to identify tumor surfaces that were not perceptible on conventional imaging. All specimens in the lesion surfaces from cyan-colored areas under NBI contained tumor cells. Specimens extracted from regions that appeared cyan in color under NBI (51.0 vessels/mm2) had significantly greater vascular density than regions that appeared a normal color (17.4 vessels/mm2; p = 0.039).

Conclusion

NBI-guided biopsy of intraventricular and paraventricular tumors is feasible for visualizing tumor surface-enhancing neovascularities. NBI would contribute to accurate histological diagnosis while minimizing injury to surrounding structures.  相似文献   
137.
Lambert‐Eaton myasthenic syndrome (LEMS) is characterized by muscle weakness, amyotrophy, easy fatigability, and depressed tendon reflexes. 3,4‐Diaminopyridine (3,4‐DAP) is the recommended therapy for the treatment of LEMS. However, estimations of 3,4‐DAP pharmacokinetics in human and animals, such as rats, are rarely reported because 3,4‐DAP is an orphan drug for the treatment of a very rare disease (LEMS). In particular, little is known about its tissue distribution. Therefore, the pharmacokinetics of 3,4‐DAP were studied, with particular focus on tissue distribution, in rats. After intravenous administration of 3,4‐DAP to rats, the half‐life of 3,4‐DAP was 15.9 ± 3.9 min and the volume of distribution at steady‐state was 2.8 ± 0.7 L/kg. The tissue‐to‐plasma partition coefficient (Kp) was high in the kidney, heart, and muscle. In addition, with increased steady state plasma concentration (Css), a tendency toward increased Kp was found in most tissues. In the muscle, a likely target region of 3,4‐DAP in LEMS patients, the Kp was higher than in the plasma. Furthermore, more than 68% of 3,4‐DAP was distributed to the muscle as determined by the ratio of 3,4‐DAP distribution calculated from the apparent volumes of distribution. Hence, 3,4‐DAP may provide for more effective and long‐lasting effects.  相似文献   
138.
Oral Radiology - The present study was performed to investigate the mineral density distribution in enamel and dentin for both permanent and primary teeth and to establish the standard density per...  相似文献   
139.
140.

INTRODUCTION

Copper deficiency leads to functional disorders of hematopoiesis and neurological system. There have been some reports of copper deficiency occurring to the patients on enteral nutrition through a jejunostomy in long-term-care hospitals. However, it is extremely rare to find patients with copper deficiency several months after esophagectomy, regardless of enteral nutrition through the jejunostomy. To the best of our knowledge, this is the first case report of a patient who experienced copper-deficiency anemia after esophagectomy and subsequent enteral nutrition through the jejunostomy.

PRESENTATION OF CASE

A 73-year-old man presented with pulmonary failure after esophagectomy for esophageal cancer with video-assisted thoracoscopic surgery, and needed long-term artificial ventilator support. Nutritional management included enteral nutrition through a jejunostomy from the early postoperative period. Copper-deficiency anemia was detected 3 months postoperatively; therefore, copper supplementation with cocoa powder was performed, and both serum copper and hemoglobin levels subsequently recovered.

DISCUSSION

Copper-deficiency anemia has already been reported to occur in patients receiving enteral nutrition in long-term care hospitals. However, this is the first case report of copper deficiency after esophagectomy despite administration of standard enteral nutrition through the jejunostomy for several months.

CONCLUSION

It is extremely rare to find copper-deficiency anemia several months after esophagectomy followed by enteral nutrition through the jejunostomy. However, if anemia of unknown origin occurs in such patients, copper-deficiency anemia must be considered among the differential diagnoses.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号